The present invention is directed to a structural assembly, formed primarily from composite matrix materials having reinforcing fibers in a polymer matrix, which may be used as a decking system or for other applications.
The need for alternative materials and configurations for load bearing decks has long been recognized. Conventional load bearing decks, such as for vehicular bridges, have historically been made from steel and concrete. While the construction techniques, and materials employed, have evolved over time for steel and/or concrete bridges, the construction process has proved to be very labor intensive, and the resulting structures have proven susceptible to corrosion and other degradations.
Partially in response to these cost and degradation issues, it has been proposed to use decking systems based on polymer composite matrix materials rather than steel and/or concrete. For instance, U.S. Pat. No. 5,794,402, incorporated herein by reference, proposes using a modular structural section formed from a polymer composite matrix to form sandwich-type load bearing deck panels for bridges. The '402 patent proposes using a plurality of polymer composite matrix core members sandwiched between upper and lower facesheets to form modular sandwich panels. The core members are described as hollow tubes, typically with a trapezoid cross-section. While the patent indicates that the tube may be made using a pultrusion process, the actual fabrication of such tubes using pultrusion has proven difficult, primarily because pultrusion of hollow tubes, with a fully enclosed passage, is technologically difficult. In simple terms, pultrusion of such hollow shapes requires the use of floating dies, which are difficult to control during manufacture. In addition, the patent teaches that layers of reinforcing fibers with so-called 45°−45°−90° orientation should be used; however, use of such 45°−45°−90° orientation layers is very expensive. Thus, while the modular and polymer composite matrix approach of the 5,974,402 patent has some theoretical advantages over traditional steel and/or concrete approaches, it has proved difficult to manufacture.
Accordingly, there remains a need for alternate composite structural assemblies that are easier and/or less costly to make and use. Ideally, such an assembly should be capable of being used for applications other than a load bearing deck, but this is not strictly required.